Freeview and FreeSat are pretty much the same thing. If you have a good signal through your aerial and your TV is relatively recent then it is likely to have Freeview built in. Most new TV's have it or FreeView HD as standard. If you have no or bad aerial, then you can use your Sky dish (even if you keep Sky). You can run another lead (you might need an adapter - your installer can do this cheaply) off the dish and plug it into a FreeSat box (Argos sell them cheaply for about ?75 for an HD version) and this will deliver a similar result to FreeView. Therefore, if you have a good aerial and a TV that has FreeView built in, then I would do that, otherwise, go the FreeSat option.